New '17 8 speed trany temp?

[Podcast]

Hey all. Just got my new Ecodiesel. Put about 30p miles on it now between the first 2 days. The temp here has been between 0 and 20 degrees Fahrenheit. My old truck with the Hemi trans in this weather was only 110 degrees. In my new truck it's between 150 and 160. Is this normal for an Ecodiesel? Seems high but not sure. A guy would think it would he the same. I can only imagine it's gonna get 180 during the summer. That's really hot for a trans.

 

[Hipps2000]

PErfectly normal...these 8speeds designed to run hotter.

 

[jlawson224]

Hey all. Just got my new Ecodiesel. Put about 30p miles on it now between the first 2 days. The temp here has been between 0 and 20 degrees Fahrenheit. My old truck with the Hemi trans in this weather was only 110 degrees. In my new truck it's between 150 and 160. Is this normal for an Ecodiesel? Seems high but not sure. A guy would think it would he the same. I can only imagine it's gonna get 180 during the summer. That's really hot for a trans.

I just traded my ED for a Cummins 2500. I had 83000 trouble free miles on the '15 Big Horn. My tranny temps on the highway we're typically 160 in the winter to 175 in the summer. Never a hiccup. The 8 speed was my favorite feature of the truck. I miss it already as now I'm in a 6-speed. I always used tow-haul mode regardless of trailer weight. Good luck with yours!

Sent from my XT1650 using Tapatalk

 

[Podcast]

Good deal. Thanks guys. My lil bro bought a '17 with the Hemi this past summer but I never looked to see what his temp was to see if it's just the tranny or otherwise. He's one of them that wouldn't have a clue what temp his tranny is at lol.

So I'm guessing that temp is the same regardless of motor?

 

[blackbetty14]

The new 8spds have a tranny heater. Basically they need to be above 77*F or something in order to fully operate normally. Mopar designed a heater that used coolant to heat the tranny fluid quicker to get it up to temp. My old 14 with the 5.7 and 6spd would rarely ever get to 160*F in the summer, my new 18 8spd will get to 170-180*F in the winter. I haven't seen max temp of the 8spd as its too cold now and ive only had the new truck a month but it should not exceed 180*F, anything over that and fluid life/clutch life drops like a rock. 160-180*F is ideal.

 

[69GWC]

pretty sure you will see temps over 180 in the summer when doing work with the truck.
pic of mine at temp

 

[tsielski]

I wish my 8-speed ran that low. Even in these cold temperatures, once all warmed up on the high way, my 8-speed temp varies between 183 and 188. Aggressive driving can get it into the 190's easily.

 

[Podcast]

That's crazy hot guys. I remember learning in auto school at college that even increasing a trans temp by 10 degrees was detrimental to the longevity. It nearly cut the trany life in half each 10 degree increment above 120 degrees. I guess time will tell if this was a good decision by RAM or not.

 

[chrisbh17]

The 8HP70 has been in use for a while now, no?

I assume if tehre were overheating issues, we would see tons of posts about it.

Im not a fan of the temps mine runs at (mid to upper 170s is the highest Ive seen) but it does seem to be able to control its heat pretty well. Just like coolant temp, it will hit 205-210 but never really go above.

 

[Podcast]

I suppose we woulda heard about issues. Not sure how many guys have over 150k on there trucks yet with the 8 speed to provide that info.

 

[chrisbh17]

I suppose we woulda heard about issues. Not sure how many guys have over 150k on there trucks yet with the 8 speed to provide that info.

The 8HP series is used in other vehicles, Ill poke around to see what their normal temperature ranges are.

 

[tsielski]

Bit of an old topic, but Mopar uses a Thermal Bypass Valve, which is integral to the transmission warmer on the Ram 8-speed. On other FCA vehicles with the 8-speed, this TBV is a small assembly installed in line with the ATF cooler lines, which in my view makes it real easy to bypass. This valve doesn't let any ATF flow to and thru the trans cooler until the fluid is at least ~179 degrees. I'm not sure at what temp that valve is fully open. The fact that some members 8-speeds run a bit cooler than others, and some run quite hot probably has to do with variations in that TBV. It's essentially a thermostat for the trans fluid.
It is removable, but difficult to get at on our Rams. The front driveshaft has to be dropped and a few other lines and brackets are directly in the way. The valve is held in place by an internal snap ring. Remove that snap ring, and the spring pressure of the valve will force the plastic sealing cap out of it's bore, and the valve then slides from that plastic cap, which can be replaced and secured with the snap ring.

I've played around with a take off transmission heater assembly. With the TBV out, ATF then will flow thru the trans cooler all the time. Pro's of doing that, and it's a big PRO, is the trans fluid will run probably ~ 20 degrees cooler, even tho it's also heated by engine coolant in the trans heater. The only Con I can think of is the trans will take longer to warm up.

Only reason I've found for Ram doing this is to eke a few tenths or hundredths of a MPG in efficiency as the hot, thinner ATF will yield a very small mileage increase. Folks on other boards have gone to the trouble to even contact ZF, the transmission design company about this, and were only told that they (ZF) take no responsibility for any thermal management systems OEM's may place on their transmission.

I may pop the TBV out of my 8-speed this coming warm season, but getting at it is involved, and I'm not ready for that thrash as yet.

 

[chrisbh17]

I stumbled on a few tech docs "introducing" the 8HP line of transmissions, and they all said the optimum temperature is around 176F. And they all also point out heaters used to get the fluid up to that temp.

Its not unique to RAM, either...Audi has a setup similar to the current RAMs, where it will direct warm/hot coolant to various areas based on priority (cabin heat first, etc) then to the transmission to get it up to temp.

 

[blackbetty14]

The basics of the 8 spd vs a 30 year old 4 speed are the same. They all use varying types of fluids based on clutch material but it all comes down to one thing. Tranny temps should not exceed 180*F for optimal transmission life. Its based on the overall basic design of the tranny, the fluid and the clutches. The 160-180*F range is the sweet zone for extended tranny life. For every 10*F there is a drastic loss in overall fluid and clutch life, doesnt matter if its synthetic or not. Unless they have come out with a crazy new clutch material and a super fluid all transmissions will and should abide by the 160-180*F rule. Getting the transmission up to temp quicker is a good idea on an electronic tranny but limiting the tranny temp is always a good thing. A too cold tranny is just as bad as a too hot.

With that being said, old 700r4s would operate in the 200-220*F zone and they wouldnt live that long (prob 100k) before a total overhaul is needed. Same thing happens with alot of other trannys, 2004R, 4L60E, 4L65E/4L80E, Old ford C4/C6, AODs yadda. Every Tranny I've rebuilt gets a custom Tranny cooling system tailored for Converter Stall and usage. I have also used Tranny thermostats when I was overcooling transmissions to get them up to the 160-180*F sweet zone.

Sounds like this little thermo valve needs to be removed. The issue is that When its stupid cold here, like now my tranny temps can be lower than 20*F and I cant idle the truck long enough to get it up to 100*F etc as that would take like 30 min or longer. So by the time I drive to work 15min or so tranny temps might reach 70*F with engine temps in the 200*F range and oil temps in the 170-180*F range. So its hard to say just remove it since these 8spds are sensitive to temp as it really only effects my tranny negatively 6 months of the year lets say.

 

[chrisbh17]

Yeah, it looks like the thermal valve thing-a-ma-jig prioritizes cabin heat, engine heat, oil heat THEN transmission heat. In our latest cold snap, my transmission is regularly 100F or less by the time I get to work with the oil at 160-ish and the coolant 190-ish.

I remote start and let it run for about 5-10 minutes before driving, but all that does really is get heat into the cabin and the coolant to a somewhat OK temp (110F or so). Oil stays "< 122" for a while, transmission Ive seen as low as 30F. I make sure to drive it gently, trying to keep it at 2K RPM or less until the oil temp drops the "<" part.

 

[blackbetty14]

Here is some interesting info on this subject in another thread about this same issue. Apparently I was correct and that the 8spd uses a very specifc fluid. Quoted from Burla.

"Basically to qualify as an oil used in the 8 speed, the oil cannot shear down much. If the oil shears down like the oils you can use in the 6 speed, the oil will not spec out for the 8 speed. So if the oil doesn't shear down in the normal operation of the 8 speed, then 180 degrees is nothing. It is like they built a transmission around an oil, as opposed to building an oil around a transmission. The only way to have a fluid start at that low of viscosity, and stay in that viscosity rating, it has to be of the highest quality base oil. I'm just trying to set your mind at ease, these 8 speeds are easy on the oil that meets the spec. The factory oil and replacements that are 25 bucks a quart are PAO, or you can opt for Redline d6 which is a better oil as in it wont drop to 5.5 visc, and as a bonus is much cheaper. Here is what redline says about the spec, so no john doe oil is going to work.

Synthetic D6 ATF is a lower viscosity version of the D4ATF and is designed for better fuel efficiency in CAFE testing... Requires a different approach to a conventional ATF formulation. Rather than beginning with a 7.5 cSt fluid and allowing a viscosity loss in use to drop to 5.5 cSt, the fluid requires a starting viscosity of less than 6.4 and a final drop to no less than 5.5 cSt. Red Line D6 will drop to no less than 6.1 cSt. ...The balanced frictional characteristics provide smooth and consistent shifts for extended drain intervals. The superior stability compared to petroleum ATFs allows high-temperature operation without varnishing valves and clutches which leads to transmission failure.

Mopar ZF atf or Redline D6 are no joke, two of the best transmission oils ever made. One PAO base, one ester base, neither will be an issue at 180F. That is why Ram doesn't even recommend you change it, they say it is a lifetime fluid."

With that being said ZF transmissions completely denies accountability for the 8spd operating temps since FCA places & Designs the thermo management system for the 8spd. ZF has no control over the transmission once it leaves there factory and the car manufactures can do as they please, FCA has admitted to placed the thermo valve to increase fuel efficency and lubrication as its main goal. But my thoughts are that the valves are rated for too high a temp and believe this was FCA trying to get all the MPG they can out of the car. I would be inclined to see if the valve could be modified to just lower the internal temp to get the best benefits of both quicker warm up and lower overall temp.

This thread also speaks about the overall design of the valve and how removing it will still mix cooled and heated fluid. So the valve isn't really a removal type of situation since the design requires permanent mods. Since its not metering filtered and unfiltered fluid and its basically just temp adjusting it seems that adjusting (lowering the temp) of the valve is the best choice. Might be a good idea to grab a replacement and see if modifying the temp opening/closing is possible, then remove the OE and replace and be done.

Heres the thread http://www.ramforum.com/threads/8hp70-transmission-heater-thermal-bypass-valve.106865/

 

[blackbetty14]

I found this but it requires the purchase of a transmission lol http://www.paramountperformanceprod...rmostatic-valve-by-paramount-performance.aspx

 

[tsielski]

Actually there are two valves associated with artificially adding heat to the 8-speeds. The first is a diverter valve, located low on the passenger side wheel well, that sends engine coolant either to cabin heat, or to the transmission heater based on ambient temperatures, and is controlled by the ECU. It sends heated coolant first to heat the cabin when it's cold, and then "diverts" the coolant to the transmission heater to heat it, once the cabin warms to a certain point.
The second is the Thermal Bypass Valve, which on our Rams, is located within the transmission heater itself. The TBV is shown below. As I mentioned in an earlier post, it is held in it's bore by an internal snap ring. Remove the snap ring, and that lower spring will force it, and the black plastic cap out. The spring assembly just has a small short rod that fits into a small opening in the center of the plastic cap. It just slides out. Then the plastic cap/o-ring can be reinstalled and secured with the snap ring.

Removing this TBV will then allow ATF to flow unimpeded to and thru the transmission cooler, but the fluid will still be heated by the heater assembly. It's unknown how much removing this alone will reduce ATF temperatures with the heater still functioning. Now one also could reach on top of the heater unit and disconnect the two coolant lines and connect them together, keeping that coolant circuit intact. If you did that, the ATF would no longer be artificially heated.

A poster mentioned modifying the TBV to have it open at a cooler temperature. Good idea, just don't know what, on the TBV would need to be modified. The entire heater assembly is made by Dana Corporation for FCA, but Dana doesn't list TBV's with different temperature settings.

 

[tsielski]

Here is a diagram showing coolant and ATF flow thru the heater.

 

[tsielski]

Here is a pic of the back side of the trans heater itself, with the TBV lying close to it's bore in the unit.